Credit: Michael Becker/FOX

UPDATED: The Idol has landed.

The 11th season debut of Fox’s American Idol had the biggest year-over-year ratings drop for a premiere episode in the show’s decade-long history. Idol delivered 21.9 million viewers and a 7.4 in the adult demo on Wednesday night, according to Fox’s time-zone-adjusted national ratings. That’s down 24 percent from last year.

The reality veteran still easily won the night (with Fox outperforming all its rivals combined) and the show will almost certainly rank as this week’s top-rated entertainment program. Still, the decline is a disappointment for Fox, though not entirely unexpected.

Here’s three reasons for the fall:

Trend: After years of growth, American Idol premiere ratings peaked in 2007 with a massive 15.8 in the demo. It’s declined nearly every year since, except in 2010 when there were considerable headlines about Ellen DeGeneres joining the show, and there was a tenth of a point uptick (even though DeGeneres didn’t actually begin judging until after the show’s premiere).

Buzz (or lack thereof): Last year, Fox shook up the Idol judging panel, adding Steven Tyler and Jennifer Lopez. So even though it declined, additional viewers likely tuned in out of curiosity. This time, with no significant format changes or judging panel shakeups, there was little to drive non-fans to check out the show. Everybody knew what they were getting.

Rivals: Here’s the most interesting factor: Idol used to be a true annual event. Fox wisely resisted the temptation to run Idol in the fall and spring, like ABC does with Dancing With the Stars and CBS with Survivor. Now, between NBC’s The Voice, The Sing Off, and America’s Got Talent, as well as Fox’s own The X Factor, there are singing auditions and judging all year around.

Point of interest: These Idol ratings have now come down to Earth enough to open the possibility of a ratings coup for NBC, which is launching season 2 of The Voice after the Super Bowl next month. Will the premiere of The Voice outperform this premiere of American Idol? Probably. But which show will win the weeks after the Super Bowl? Ever since Idol became Fox’s Death Star, there hasn’t been another series that’s had a more realistic shot of toppling Idol in the adult demo on a weekly basis (Dancing has occasionally beat Idol among total viewers).

Also Wednesday: The Lily-says-the-f-word episode of Modern Family aired despite some protests. The show impressed by remaining almost steady in the ratings against Idol, with 11.8 million viewers and a 5.0 rating, down a mere 2 percent from last week.

But Idol proved it could still have a strong negative impact on most other mortal shows: ABC’s The Middle (8.2 million, 2.6) was down 10 percent, Suburgatory (7 million, 2.5) dropped 14 percent and Happy Endings (6.2 million, 2.9) was down 3 percent. At 10 p.m., Revenge (2.5) climbed 4 percent. On CBS, Criminal Minds (12.8 million, 3.2) was down 6 percent, CSI (11.8 million, 2.8) was down 3 percent. NBC sacrificed Whitney (4.3 million, 1.6) to the Idol gods, down 20 percent to a series low, followed by Are You There, Chelsea (4.3 million, 1.8), down 22 percent, and Harry’s Law (6.4 million, 1.1), down 8 percent. On The CW, One Tree Hill (1.5 million, 0.7) was down 22 percent.

Read more: